Sentencing a juvenile to spend the rest of his or her life in prison for a nonhomicide crime without any opportunity for release on parole is cruel and unusual punishment in violation of the Constitution’s Eighth Amendment.

In a 6-to-3 decision announced on Monday, the US Supreme Court declared for the first time that juveniles convicted of crimes that are not fatal to the victim must be given a meaningful opportunity to win release on parole.

“This court now holds that for a juvenile offender who did not commit homicide the Eighth Amendment forbids the sentence of life without parole,” Justice Anthony Kennedy wrote in the majority decision. “This clear line is necessary to prevent the possibility that life without parole sentences will be imposed on juvenile nonhomicide offenders who are not sufficiently culpable to merit that punishment.”

In a dissent, Justice Clarence Thomas said Congress, the District of Columbia, and 37 states currently allow judges and juries to decide when – or if – life without parole is an appropriate sentence for a juvenile offender.

“I am unwilling to assume that we, as members of this court, are any more capable of making such moral judgments than our fellow citizens,” he wrote. “Nothing in our training as judges qualifies us for that task, and nothing in [the Constitution] gives us that authority.”

Reasoning follows that of 2005 case

In invalidating the sentence of a Florida man convicted at age 17, the majority justices applied the same constitutional reasoning used in a 2005 decision in which the high court ruled 5 to 4 that imposing the death penalty on juvenile offenders violated the Eighth Amendment. The key fifth vote in the 2005 case was cast by Justice Kennedy.

Monday’s decision comes in a case called Graham v. Florida. Terrance Graham was sentenced to life without parole by a Florida state judge after Mr. Graham violated his probation for an earlier offense and committed a series of violent, armed home invasion robberies. Graham pleaded guilty. He was 17.

Florida officials defended the life sentence as reflective of a balance struck by state lawmakers and Florida judges.

The majority justices disagreed. “Terrance Graham’s sentence guarantees he will die in prison without any meaningful opportunity to obtain release, no matter what he might do to demonstrate that the bad acts he committed as a teenager are not representative of his true character, even if he spends the next half century attempting to atone for his crimes and learn from his mistakes,” Kennedy wrote.

“The state has denied him any chance to later demonstrate that he is fit to rejoin society based solely on a nonhomicide crime that he committed while he was a child in the eyes of the law,” Kennedy said.

The high court ruling makes clear that states retain the ability to imprison the worst juvenile offenders for the rest of their lives. The point of the ruling is that even the worst juvenile offenders must be given an opportunity to obtain release based on demonstrated maturity and rehabilitation.

“Those who commit truly horrifying crimes as juveniles may turn out to be irredeemable, and thus deserving of incarceration for the duration of their lives,” Kennedy said. “The Eighth Amendment does not foreclose the possibility that persons convicted of nonhomicide crimes committed before adulthood will remain behind bars for life. It forbids states from making the judgment at the outset that those offenders never will be fit to reenter society.”

Dissent: not judges' job to decide sentence

In his dissent, Thomas criticized the majority’s willingness to move the line of Eighth Amendment jurisprudence by citing the nation’s “evolving standards of decency.”

“The ultimate question in this case is not whether a life-without-parole sentence ‘fits’ the crime at issue here or the crimes of juvenile nonhomicide offenders more generally, but to whom the Constitution assigns that decision,” Thomas wrote.

“The fact that the court categorically prohibits life-without-parole sentences for juvenile nonhomicide offenders in the face of an overwhelming legislative majority in favor of leaving that sentencing option available under certain cases” he said, “simply illustrates how far beyond any cognizable constitutional principle the court has reached to ensure that its own sense of morality and retributive justice pre-empts that of the people and their representatives.”

Thomas’s dissent prompted a reply from Justice John Paul Stevens, defending the court’s recognition of evolving standards of decency. “Society changes. Knowledge accumulates. We learn, sometimes, from our mistakes,” Justice Stevens wrote. “Punishments that did not seem cruel and unusual at one time may, in the light of reason and experience, be found cruel and unusual at a later time.”

He added, “Standards of decency have evolved since 1980. They will never stop doing so.”

Thomas replied in his dissent: “I agree with Justice Stevens that we learn sometimes from our mistakes. Perhaps one day the court will learn from this one.”

In addition to Graham’s case, the high court heard a tandem case involving 13-year-old Joe Sullivan, who was sentenced to life without parole after being convicted of beating, raping, and robbing a 72-year-old woman. Rather than deciding that case or applying the holding in the Graham case to Sullivan, the court dismissed the Sullivan case as improvidently granted.